Hematological and Histopathological Changes of Juvenile Grass Carp (Ctenopharyngodon idella) Exposed to Lethal and Sublethal Concentrations of Roundup (Glyphosate 41% SL)

Abstract

The presence of pesticides and their potential toxic effects on fish can pose a threat to aquatic ecosystems and human health. The present study aimed to evaluate the effect of commercial formulations of glyphosate (Roundup) on the survival rate, hematological parameters, and tissues (gills and liver) of juvenile grass carp (Ctenopharyngodon idella). For these purposes, we exposed the fish to 0, 50, 100, and 150 mL L-1 of Roundup for 96 hr. Results showed a significant correlation between the fish's mortality rate and pesticide concentrations (p<0.01); the LC50 96 hr of Roundup was 75.838 mL L-1 in the present study. The concentrations above 50 mL L-1 induced significant tissue lesions seen as lamellar aneurism, leukocyte infiltration, distal hyperplasia, cloudy swelling, macrophage aggregates, and necrosis in the gills and liver. We also reported a significant correlation between the severity of tissue damage and Roundup concentration. The hematocrit, hemoglobin, white, and red blood cell count significantly reduced after 96 hr of exposure to 100 and 150 mL L-1. The opposite trend was reported for concentrations of glucose, albumin, cholesterol, total protein, and triglycerides. Finally, the fish exposed to 100 and 150 mL L-1 of Roundup displayed some clinical signs, such as increasing operculum movement, darkening the skin, and swimming near the surface during the movement test. Overall, our results showed that concentrations of Roundup higher than 50 mL L-1 can induce various toxic effects and significantly reduce the survival chance of juvenile grass carp. Roundup altered fish behavior, tissue functioning, and biochemical processes. In this study, we provided some basic knowledge about the effects of a glyphosate-based herbicide on aquatic organisms and possible environmental management.